How to prepend labels to each log line?

Hello! I want to prepend and concatenate some labels to every single log line within Loki. For example, instead of my log line being just

Hello World!

I want it to instead read

machine1.test Hello World!

assuming that there are labels node=machine1 and app=test. How can I do this with a Loki query? Thanks!

This sounds like a perfect question for @ewelch

Ed: Any suggestions?